I only have done it from chick stage, but would prefer that. Possible diseases, and also behavior issues are first things that come to mind. For instance, I had tiny roosts in their box from day one, and they used them. Mine need no ladders in their coop. They hop up to the 24" ht roost, then on up to the 48" ones. Ditto for nesting boxes.
Also, I have fed mine tons of living greens and also fruit and veggie scraps from day one. I never needed calcium added until at 16 weeks when I saw the first egg. From then on, I added calcium to their food. Until then, I trusted in the raw fresh greens to give them their calcium needs. I also now recycle the shells into their food . I have 24 healthy pullets. One is a runt and a cripple tho with a limp, probably due to a mid-air collision with another bird (they are spastic).